What is 'Disease X?'

What is "Disease X?" The World Health Organization just added the new disease to its list of nine illnesses that could spark a worldwide epidemic. Disease X represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown. World Health Organization WHO's purpose of adding this mysterious malady to its list was to acknowledge that infectious diseases are unpredictable. The organization said "Disease X" is intended to prepare the public for all threats.